This is often implemented in a way that the label in the value of the @ value attribute of input element or the content of the textarea element is set, the training and insertion is done by JavaScript. The technical implementation is problematic:
Caption and actual user input must be distinguished in the field and the text style (color) must be changed with JavaScript. Should also be pre-assigned fields are used, the distinction made in the markup (HTML).
If the JavaScript is running late, the user enters something into the field before its label was deleted. Thereby, the label text undesirable to a portion of the input.
Circumvents this difficulty, if one realizes the labeling with the appropriate HTML label element. This is encapsulated together with the input field in a container element of the class “label inside”:
